PROFINET can help you justify your project as these features have financial rewards:
Feature: proxies.
Benefit: Maps legacy networks into PROFINET using an open standard.
The money: no need to rip and replace. Leave your current network intact and add a proxy to integrate the devices into a new PROFINET-based controller. Gain the benefits of the new controller and PROFINET network: faster speed, more bandwidth, and upward integration.
Feature: redundant media, devices, and controllers.
Benefit: fault tolerance.
The money: more uptime. A single failure will not shut down the line; production continues while the failure is fixed. Media – a break in a cable will not shut down the line. Ring topology for redundancy means communications continues from 
the other direction. Device – a device fails? No problem; a replacement device is sitting on the network ready to take over its function. Controller – if a controller fails, a “hot standby” controller is available that communicates with the primary controller to ensure seamless transition to the standby. If the cable breaks – no downtime. If a device fails – no downtime. If a controller fails – no downtime.
Feature: diagnostics.
Benefit: quick recovery from failure.
The money: less downtime. PROFINET provides two levels of diagnostics: PROFINET-specific and leveraging IT protocols. PROFINET-specific diagnostics provide details of device failure, module failure, and channel failure. IT protocols of HTTP, SNMP, and LLDP are required in PROFINET devices and provide network diagnostics. HTTP allows web server/browser traffic from controllers, Ethernet switches, and more. SNMP tracks switch port failures and retries with additional data. LLDP allows devices to know what is connected to their ports. For more details see “PROFI Diagnostics” and “PROFINET IO Device Diagnostics – An Overview.” Some of the diagnostic capabilities don’t just shorten downtime, they prevent it!
Feature: support.
Benefit: help when and where you need it.
The money: It’s not easy to put a price tag on support, but that does not mean it does not have value. PROFINET and PROFIBUS are the only technologies sponsored by an organization represented in every region, including PI Competence Centers (PICCs). These competence centers provide support to users and device makers. Need to call someone with a question about the network? Call a PICC. See “Around the World in 50 Competence Centers.”
As a control engineer I get excited by the features of PROFINET. But it’s good to know I can justify using it based on sound financial principles.
–Carl Henning
UPDATE: For those of you who could not fathom my Twitter challenge of how the title of this post relates to Cuba – in the movie Jerry Maguire, “Show me the money” was first uttered by actor Cuba Gooding Jr. You all are forgiven for not wandering down the circuitous path my mind sometimes takes me.